a) Field of the invention
The present invention relates to an apparatus for printing an image recorded on a film onto a photosensitive material, and particularly to an apparatus for printing an image onto a photosensitive material, after a film is positioned at a predetermined position on the photosensitive material, and to a device for positioning the film.
b) Description of the Related Art
An image recorded on an original film (hereinafter referred to as a negative film) is printed onto a lithographic printing plate, which is used in a rotary press or the like for printing newspaper, or a photosensitive material such as a photosensitive material for preparing a color proof (hereinafter referred to as a PS plate) by means of an apparatus for printing a photosensitive material (hereinafter referred to as a printing apparatus for printing plate).
A surface plate is disposed at the printing station of this printing apparatus for printing plate. A PS plate supplied onto the printing apparatus by means of a PS plate feeding apparatus is placed on the surface plate at a predetermined position. At this time, the negative film is placed while being positioned or registered at a predetermined position of the PS plate. In this positioning, a protrudent portion, for example, a pin or the like, is provided on the surface plate, and is inserted into a hole formed in the negative film to register the negative film. In addition, this positioning is conducted on the basis of the position o f an image area indicating mark (hereinafter referred to as a register mark) marked on the negative film.
High accuracy is required for the positioning of the negative film on the PS plate. After the negative film is placed on the PS plate, it is further necessary to finely adjust the position of the negative film.
In addition, in particular, in color printing, if separation negative films, corresponding to four color separated images of yellow, magenta, cyan and black, are used, it is necessary to separately print the images of the four separation negatives onto the PS plate. Therefore, according to the above-described positioning method, the color-separated image of the negative film is printed onto the PS plate four times, in which accurate positioning of each negative film is required. Namely, the negative films are required to be accurately registered on the PS plate to be printed so as not to cause color shift in a color image printed by superposing these four color images.
However, according to the above-described printing apparatus for printing plate, since the positioning of the negative films is conducted after the negative films are placed on the PS plate, the positioning process requires tens of seconds. Accordingly continuous printing of a plurality of negative films is time-consuming. In addition, it is necessary to use an identical printing apparatus, in order to prevent the color shift of the color image due to dimension of a positioning error among the printing apparatuses for printing plate, which in turn complicates the printing work and may effect the working efficiency.